Method and system for execution profiling using loop count variance

1. A non-transitory computer readable storage medium having computer readable program code embodied therein, the computer readable program code adapted to, when executed by a processor, implement a method for executing a computer program, the method comprising:

upon entry into a loop included in the computer program:

incrementing an entry counter by one;

for each iteration of a plurality of iterations of the loop:

incrementing an iteration counter by one;

incrementing a local counter by one to obtain an incremented value of the local counter;

increasing a value of a summation variable by the incremented value of the local counter; and

executing the iteration of the loop; and

calculating a variance for the number of iterations per entry into the loop using the entry counter, the value of the summation variable, and the iteration counter to obtain an execution profile for the loop.

2. The non-transitory computer readable storage medium of claim 1 , further comprising, upon entry into the loop, setting the local counter to zero.

3. The non-transitory computer readable storage medium of claim 1 , wherein the entry counter, the iteration counter, and the summation variable are stored in the execution profile associated with the loop.

4. The non-transitory computer readable storage medium of claim 1 , wherein the loop is one of a plurality of loops included in the computer program.

5. The non-transitory computer readable storage medium of claim 4 , wherein each of the plurality of loops is associated with a different execution profile.

6. The non-transitory computer readable storage medium of claim 1 , further comprising using the entry counter and the iteration counter to calculate an average number of iterations per entry into the loop.

7. The non-transitory computer readable storage medium of claim 1 , further comprising determining whether the variance is above a predefined threshold.

8. The non-transitory computer readable storage medium of claim 7 , further comprising, upon determining that the variance is above a predefined threshold, compiling the loop into a generalized version of the loop.

9. The non-transitory computer readable storage medium of claim 7 , further comprising, upon determining that the variance is not above a predefined threshold, compiling the loop into a specialized version of the loop.

10. A non-transitory computer readable storage medium having computer readable program code embodied therein, the computer readable program code adapted to, when executed by a processor, implement a method for executing a computer program, the method comprising:

upon entry into a loop included in the computer program:

incrementing an entry counter by one;

setting a local counter to zero;

for each iteration of the loop:

incrementing an iteration counter by one;

incrementing the local counter by one to obtain an incremented value of the local counter;

increasing a value of a summation variable by the incremented value of the local counter;

executing the iteration of the loop;

calculating a variance for the number of iterations per entry into the loop using the entry counter, the value of the summation variable, and the iteration counter to obtain an execution profile for the loop; and

compiling an optimized version of the loop using the execution profile.

11. The non-transitory computer readable storage medium of claim 10 , wherein the loop is one of a plurality of loops included in the computer program.

12. The non-transitory computer readable storage medium of claim 11 , wherein each of the plurality of loops is associated with a different execution profile.

13. The non-transitory computer readable storage medium of claim 10 , wherein compiling the optimized version of the loop comprises using the entry counter and the iteration counter to calculate an average number of iterations per entry into the loop.

14. A system, comprising:

a processor;

a physical memory; and

a computer usable storage medium having computer readable program code embodied therein, the computer readable program code adapted to, when executed by the processor, implement a method for executing a computer program, the method comprising:

obtaining a statement of the source code, wherein the statement comprises a method call, and wherein the source code is composed in a statically-typed programming language;

upon entry into a loop included in the computer program:

incrementing an entry counter by one;

for each iteration of the loop:

incrementing an iteration counter by one;

incrementing a local counter by one to obtain an incremented value of the local counter;

increasing a value of a summation variable by the incremented value of the local counter; and

executing the iteration of the loop; and

calculating a variance for the number of iterations per entry into the loop using the entry counter, the value of the summation variable, and the iteration counter to obtain an execution profile for the loop.

15. The system of claim 14 , the method further comprising, upon entry into the loop, setting the local counter to zero.

16. The system of claim 14 , wherein the entry counter, the iteration counter, and the summation variable are stored in the execution profile associated with the loop.

17. The system of claim 14 , the method further comprising using the entry counter and the iteration counter to calculate an average number of iterations per entry into the loop.